Methods and apparatus for dielectric deposition

ABSTRACT

Methods for depositing flowable dielectric films are provided. In some embodiments, the methods involve introducing a silicon-containing precursor to a deposition chamber wherein the precursor is characterized by having a partial pressure:vapor pressure ratio between 0.01 and 1. In some embodiments, the methods involve depositing a high density plasma dielectric film on a flowable dielectric film. The high density plasma dielectric film may fill a gap on a substrate. Also provided are apparatuses for performing the methods.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority to U.S.application Ser. No. 12/964,110, filed Dec. 9, 2010, which claims thebenefit of priority to U.S. Provisional Patent Application No.61/285,091, filed Dec. 9, 2009, all of which are incorporated herein byreference in their entireties and for all purposes.

BACKGROUND OF THE INVENTION

It is often necessary in semiconductor processing to fill high aspectratio gaps with insulating material. This is the case for shallow trenchisolation (STI), inter-metal dielectric (IMD) layers, inter-layerdielectric (ILD) layers, pre-metal dielectric (PMD) layers, passivationlayers, etc. As device geometries shrink and thermal budgets arereduced, void-free filling of narrow width, high aspect ratio (AR)features (e.g., AR>6:1) becomes increasingly difficult due tolimitations of existing deposition processes.

SUMMARY OF THE INVENTION

Methods for depositing flowable dielectric films are provided. In someembodiments, the methods involve introducing a silicon-containingprecursor to a deposition chamber wherein the precursor is characterizedby having a partial pressure:vapor pressure ratio between 0.01 and 1. Insome embodiments, the methods involve depositing a high density plasmadielectric film on a flowable dielectric film. The high density plasmadielectric film may fill a gap on a substrate. Also provided areapparatuses for performing the methods.

The detailed description below will further discuss the benefits andfeatures of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A includes schematic cross-sectional depictions of unfilled gapsin a shallow trench isolation (STI) integration process.

FIGS. 1B and 1C are schematic cross-sectional depiction of gaps filledby a method according to certain embodiments.

FIG. 2A is a process flow diagram illustrating operations in a method offilling trenches or other gaps with dielectric material according tocertain embodiments.

FIG. 2B includes schematic cross-sectional depictions of operations inFIG. 2A.

FIG. 3A is a process flow diagram illustrating operations in a method offilling trenches or other gaps with dielectric material according tocertain embodiments.

FIG. 3B includes schematic cross-sectional depictions of operations inFIG. 3A.

FIG. 4A is a process flow diagram illustrating operations in a method offilling trenches or other gaps with dielectric material according tocertain embodiments.

FIG. 4B includes schematic cross-sectional depictions of operations inFIG. 4A.

FIG. 5A is a process flow diagram illustrating operations in a method offilling trenches or other gaps with dielectric material according tocertain embodiments.

FIG. 5B includes schematic cross-sectional depictions of operations inFIG. 5A.

FIG. 6A includes a schematic cross-sectional depiction of incomingaspect ratio (AR) and AR after flowable oxide deposition in features ofvarious sizes. FIG. 6A also includes a plot of aspect ratio for varioussized features before and after flowable deposition.

FIG. 6B is another plot of aspect ratio for various sized featuresbefore and after flowable deposition. Images of gaps filled withflowable oxide and an HDP oxide cap are shown on the plot.

FIG. 7 is a process flow diagram illustrating operations in a method ofdepositing flowable dielectric material in gaps according to certainembodiments.

FIGS. 8A-8D are schematic depictions of reaction mechanisms in anexample of a method of filling a gap with dielectric material accordingto certain embodiments.

FIG. 9A is a graph qualitatively illustrating the tunability of featurefill selectivity.

FIG. 9B is a plot illustrating the dependence of fill height for aparticular feature size on solvent partial pressure.

FIG. 10 is a process flow diagram illustrating operations in a method ofdepositing flowable dielectric material in gaps according to certainembodiments.

FIG. 11 is a process flow diagram illustrating operations in a method ofdepositing flowable oxide in a gap in a silicon or SOI substrateaccording to certain embodiments.

FIG. 12 is a process flow diagram illustrating operations in method offilling a gap with dielectric material according to certain embodiments.

FIG. 13 is a top view diagram illustrating a multi-station apparatussuitable for practicing selected embodiments.

FIG. 14 is simplified illustration of a HDP-CVD module suitable forpracticing various embodiments.

FIG. 15 is a simplified illustration of a direct plasma deposition/curemodule suitable for practicing various embodiments.

FIG. 16 is a simplified illustration of a remote plasma deposition/curemodule suitable for practicing various embodiments.

DETAILED DESCRIPTION OF THE INVENTION Introduction

The present invention pertains to methods of filling gaps on asubstrate. In certain embodiments, the methods pertain to filling highaspect (AR) ratio (typically at least 6:1, for example 7:1 or higher),narrow width (e.g., sub-50 nm) gaps. In certain embodiments, the methodspertain filling both low AR gaps (e.g., wide trenches). Also in certainembodiments, gaps of varying AR may be on the substrate, with theembodiments directed at filling low and high AR gaps.

According to various embodiments, the methods involve depositing bothflowable oxide films and high density plasma chemical vapor depositionoxide (HDP oxide) films in a gap. According to various embodiments, theflowable oxide films may be used as a sacrificial layer and/or as amaterial for bottom up gap fill. In certain embodiments, the top surfaceof the filled gap is an HDP oxide film. The resulting filled gap may befilled only with HDP oxide film or a combination of HDP oxide andflowable oxide films. The methods provide improved top hat reduction andavoid clipping of the structures defining the gaps.

As used herein, the term “HDP oxide film” refers to doped or undopedsilicon oxide films deposited using high density plasma chemical vapordeposition processes. Generally, a high density plasma is any plasmahaving electron density of at least about 5×10¹⁰ electrons per cubiccentimeter, and more typical 1×10¹¹ electrons per cubic centimeter. HDPCVD reactions may also be characterized in certain embodiments, byrelatively low reactor pressures, in the range of 100 mTorr or lower.

While the below description refers chiefly to HDP oxide cap films, othertypes of dielectric films may be used including TEOS oxide deposited byplasma enhanced chemical vapor deposition (PECVD), sub-atmospheric CVD(SACVD) or dielectric deposited by any other method.

As used herein, the term “flowable oxide film” is a flowable doped orundoped silicon oxide film having flow characteristics that provideconsistent fill of a gap. The flowable oxide film may also be describedas a soft jelly-like film, a gel having liquid flow characteristics, aliquid film, or a flowable film. Unlike HDP-CVD reactions, forming aflowable film may involve reacting a silicon-containing precursor and anoxidant to form a condensed flowable film on the substrate. Formation ofthe film may be aided by a catalyst, e.g., as described in U.S. patentapplication Ser. No. 11/925,514, filed Oct. 26, 2007, incorporated byreference herein. The flowable oxide deposition methods described hereinare not limited to a particular reaction mechanism, e.g., the reactionmechanism may involve an adsorption reaction, a hydrolysis reaction, acondensation reaction, a polymerization reaction, a vapor-phase reactionproducing a vapor-phase product that condenses, condensation of one ormore of the reactants prior to reaction, or a combination of these. Thesubstrate is exposed to the process gases for a period sufficient todeposit a flowable film to fill at some of the gaps. The depositionprocess typically forms soft jelly-like film with good flowcharacteristics, providing consistent fill. In certain embodiments, theflowable film is an organo-silicon film, e.g., an amorphousorgano-silicon film.

As deposited HDP oxide films are densified solids and not flowable,whereas as-deposited flowable oxide films are not fully densified. Theterm “flowable oxide film” may be used herein to refer to flowable oxidefilms that have undergone a densification process that wholly orpartially densifies the film and/or a conversion process that wholly orpartially chemically converts the film as well as as-deposited flowableoxide films. Details of HDP-CVD and flowable oxide deposition processesare described further below.

While the description below refers chiefly to flowable silicon oxidefilms, the integration schemes described herein may also be used withother types of flowable dielectric films. For example, the filmas-deposited may be primarily silicon nitride, with Si—N and N—H bonds,or silicon oxynitride. In certain embodiments, such films may beconverted by a cure process to a SiO or SiON network.

In certain embodiments, shallow trench isolation (STI) integrationmethods are provided. FIG. 1A depicts cross-sectional schematicrepresentations of dense (at 101) and isolated (at 102) gaps to befilled in an STI process. At 101, gaps 104 a-104 d are trenches formedin a silicon or silicon-on-insulator (SOI) substrate 103. Pad oxidelayer 105 and silicon nitride layer 106 are also depicted. The sidewallsof the trench may also be coated with an oxide layer or a liner layer(not shown), for example a SiON or SiN layer. At 102, an isolated gap104 formed in a silicon or SOI substrate 103 is depicted. Although notshown, the sidewalls of gap 104 may also be defined by oxide, nitrideand other layers. While the gaps depicted schematically in FIG. 1A havea generally square profile, the sidewalls of the gap may be slanted,e.g., as depicted schematically in FIG. 6, below.

A gap typically is defined by a bottom surface and sidewalls. The termsidewall or sidewalls may be used interchangeably to refer to thesidewall or sidewalls of a gap of any shape, including a round hole, along narrow trench, etc. The sidewall and bottom surfaces that definethe gap may be one or multiple materials. Examples of gap sidewall andbottom materials include nitrides, oxides, carbides, oxynitrides,oxycarbides, silicides, as well as bare silicon or other semiconductormaterial. Particular examples include SiN, SiO₂, SiC, SiON, NiSi, andany other silicon-containing material. In certain embodiments, prior toflowable dielectric deposition, the gap is provided with a liner,barrier or other type of conformal layer formed in the gap, such thatall or a portion of the bottom and/or sidewalls of the gap is theconformal layer.

A gap may also be characterized by the structures it lies between. Incertain embodiments, such as in the examples depicted in FIG. 1A, thestructures are or include areas of a silicon substrate between gapsetched into the substrate. The structures (also referred to herein asraised features or features) may also be, for example, hardmasks, metalvias or trench lines, transistor gates or other features. Adjacentstructures define a gap there-between. The structures may include one ormore liner layers that form the sidewalls of the gap.

In gaps that are filled solely with HDP oxide, in addition to fill ofHDP oxide at the bottom of the gaps, HDP oxide is deposited on top ofthe structures (top hats) and overhangs and cusps at the entry region ofthe gap to be filled. The overhang formations result from sputtering andredeposition processes. The directional aspect of the deposition processproduces some high momentum charged species that sputter away materialfrom within the gap. The sputtered material tends to redeposit on thesidewalls of high AR structures. If allowed to grow, the cusps depositedon the sidewalls of the feature can prematurely close-off the gap. Toremove these cusps and top hat formations, an etch back process isperformed. The etching is accomplished by exposure to afluorine-containing compound, e.g., a plasma containing fluorinespecies. These species normally originate from a fluorine-containingprocess gas component such as SiF₄, SiH₂F₂, Si₂F₆, C₂F₆, NF₃, CF₄, andthe like. Other etch processes may also be employed such as a wet etchin HF.

The etch is limited by clipping of the structure by the etchants,typically at top corner of structure or sidewall of gap, as shown.Clipping refers to damage due to the exposure of the structure toetchants and may be the result of either physical or chemical etchprocesses. Clipping causes problems in subsequent process steps, such aslack of CMP polish stop due to SiN erosion, and problems in electricalperformance, such as clipping (erosion) into a Si sidewall in trenches.For example, an NF3 etch of an HDP oxide deposited in a high AR gap nextto a wide gap (such as a trench) can result in sidewall clipping of thehigh AR feature by lateral chemical etch by NF3, due to thin sidewallcoverage. For advanced structure, the deposition amount per cyclebecomes thinner, resulting in a disappearing NF3 etch process window.

FIG. 1B is a representation of gaps 104 filled according to certainembodiments. In the depicted embodiment, each gap 104 is filled withdielectric material, a flowable dielectric material 110 and HDP oxidematerial 112. According to various embodiments, the flowable dielectricmaterial 110 fills the gap to a level beneath that of silicon nitridelayer 106. According to various embodiments, the flowable dielectricmaterial 110 is at least 50 nm from the bottom of the silicon nitridelayer 106. A wide trench 114 filled with HDP oxide 112 is also depictedin FIG. 1B. A small amount of flowable dielectric 110 a is present onthe depicted sidewall of trench 114; as with the flowable dielectricmaterial in narrow gaps 104, it is at least 50 nm or so below thesilicon nitride layer of that sidewall.

In certain embodiments, there is substantially no flowable oxidedeposition on the sidewall in narrow gaps above the level of theflowable oxide deposition; that is to say that there is substantially noconformal component to the bottom up flowable oxide deposition. FIG. 1Cdepicts a cross-section a gap partially filled with flowable oxide 110,with the remainder of the gap filled with HDP oxide 112. A capillarycondensation reaction mechanism used in certain embodiments to depositthe flowable oxide and described further below results in bottom up flowwith a concave meniscus, as shown. Above the meniscus, deposition on thesidewall is no more than about 1 monolayer, or less than about 4Angstroms, per flowable oxide deposition cycle; with total deposition(depending on the number of cycles) on the sidewalls less than twentyAngstroms or less than ten Angstroms for example. This results insubstantially all HDP oxide in the gap above the flowable oxide level(e.g., at least 50 nm below a SiN layer). This beneficial as asubstantial amount of flowable dielectric sidewall deposition (e.g., 100Angstroms or more) may result in unwanted etching at the sidewall duringlater processes in which the HDP oxide is etched.

According to various embodiments, the methods of the invention provideimproved gap fill by using a flowable oxide film as a sacrificial filmduring HDP-CVD gap fill and/or using a flowable oxide film for bottom upgap fill in conjunction with HDP oxide, as shown in FIG. 1B. Accordingto various embodiments, an unfilled gap is provided, with HDP oxide andflowable oxide deposition processes used to deposit HDP oxide andflowable oxide in the gap. According to various embodiments, the HDPoxide may be deposited first, followed by the flowable oxide orvice-versa. In certain embodiments, the final deposition operation is anHDP-CVD operation such that top surface of the filled gap is HDP oxide.One or more etch operations may be performed after various depositionoperations to etch back HDP oxide and/or flowable oxide. The etchoperations may be non-selective (etching both HDP oxide and flowableoxide material) or selective (etching primarily or solely flowable oxideor HDP oxide while leaving the other substantially un-etched). FIG. 1Bprovides an example of filled gaps according to one process scheme.Various embodiments are set forth below as examples of process schemes.

FIG. 2A is a process flow diagram illustrating an embodiment in whichflowable oxide film is used as a sacrificial material to reduce top hatformation while protecting feature sidewalls from the deleteriouseffects of chemical etchants. The process begins by providing asubstrate having raised features and unfilled gaps between the raisedfeatures (201). Unfilled generally refers to unfilled with insulationmaterial that is to be deposited to fill the gap; as indicated above,various liner or other layers may be present in the gap. The substrateis provided to an HDP-CVD reactor, additional details of which aredescribed below. One or more HDP-CVD deposition operations may then beperformed to partially fill the gap with HDP oxide dielectric material(203). Further details of HDP-CVD deposition processes and parametersare given below. If multiple deposition operations are to be performed,in certain embodiments, they may be interspersed with one or moreintervening etch operations and/or an etch operation may be performedafter the one or more HDP-CVD deposition operations, e.g. to remove cuspmaterial. In certain embodiments, however, no etch operations areperformed prior to the flowable oxide deposition. After HDP-CVDdeposition to partially fill the gap, HDP oxide is in the bottom of thegap, on the sidewalls and on top of the raised features (top hats). Thesidewall deposition is typically characterized by a narrowing of the gapfrom a bottom-up perspective, with the most deposition occurring at theentry to the gap. This can be seen in the cross-sectionalrepresentations of a partially filled gap after HDP-CVD deposition inFIG. 2B, which depicts features and gaps at various stages of a processas described in this example. At 220, top hats 221 and cusps 223 formedby deposited HDP oxide 112 are depicted. Returning to FIG. 2A, the nextoperation involves depositing flowable oxide film to overfill the gap(205). That is, enough flowable oxide film is deposited to fill the gapas well as cover the features. In certain embodiments, the HDP oxide tophats are also covered by the flowable oxide film. This is depicted inFIG. 2B as 230, with flowable oxide film 110 filling the gaps andcovering HDP oxide top hats 221. Details of the flowable oxidedeposition are described further below. According to variousembodiments, the flowable oxide deposition may occur in the HDP-CVDdeposition chamber or in a separate deposition chamber. In certainembodiments, it may occur in a different station of a multistationchamber. Also in certain embodiments, different process modules areattached on one mainframe. Thus, depending on the embodiment,transitioning between HDP-CVD deposition and flowable oxide depositionmay or may not involve transferring the substrate to a different chamberor process module. Note also that if an etch operation is performedbetween these operations, it may involve transfer to and from a separateetch chamber. Once the flowable oxide is deposited, an optional cureoperation may be performed (207). As described below, in the cureprocess, the film may be densified and/or chemically converted to adesired dielectric composition. In certain embodiments, thedensification and conversion are performed in separate operations; ormultiple operations may be performed, each densifying and/or curing thefilm. Still in other embodiments, the as-deposited film may bechemically converted without densification or vice versa. In certainembodiments, cure of the flowable film may be used to tune etchcharacteristics of the flowable film. In the next operation, anon-selective removal of HDP oxide and flowable oxide is performed;depending on the removal chemistry and process used and thecharacteristics of the flowable oxide and HDP oxide, performing a cureprocess may be useful to harmonize the etch rates of these films. Asdiscussed further below, various cure processes may be performed. Theseprocesses may densify the film and may completely solidify it in certaincases. In certain embodiments, only a top portion that is to be etchedthe succeeding operation is cured. In this manner different etchcharacteristics can be imparted to the top portion of the flowable oxidefilm, which is to be non-selectively removed, and the bottom portion ofthe film, which is to be selectively removed. A partially cured film isdepicted at 240 in FIG. 2B in which a portion 110 b of the flowableoxide film 110 that is above the gap is cured. Portion 110 b may bedensified and/or chemically converted to a silicon oxide (or otherdesired dielectric). In certain embodiments, portion 110 c remaining inthe gap is lower density than portion 110 b, but is still chemicallyconverted to a SiO network. In other embodiments, portion 110 c iscompositionally different than portion 110 c. In certain embodiments, nocure operation is performed, with the etch chemistry or conditionssuitably to remove the desired film(s). As indicated, a non-selectiveremoval of HDP oxide and flowable oxide is performed (209). The etchstops above the raised features and the gap openings, but removes atleast a portion of the top hat deposition, in certain embodiments, mostof the top hat deposition. This is depicted at 250 in FIG. 2B, whichshows only a thin layer of HDP oxide 112 above the features and the gapopening. The remaining flowable oxide film may then be optionally cured,e.g., to modify its etch characteristics (211). The remaining flowableoxide is then selectively removed, that is it is removed withoutremoving a significant amount of the HDP oxide (213). This is depictedat 260 in FIG. 2B, with only HDP oxide 112 remaining. This may be doneusing the same or a different removal process as performed in operation209, for example a wet etch rather than a plasma etch may be used.Operations 203-213 may then be repeated to further partially fill thegap with HDP oxide, overfill the gap with a sacrificial layer of aflowable oxide film, remove HDP oxide and flowable oxide from above thefeatures and gap, and selectively remove the flowable oxide from the gap(215). If these operations are not repeated, or after one or more suchrepetitions, one or more additional HDP-CVD depositions are performed tocomplete fill of the gap with HDP oxide (217). In certain embodimentswherein multiple depositions are performed, intervening etch operationsmay be performed. Alternatively, the gap fill may be completed withoutadditional etch operations. The resulting gap is filled with HDP oxide,with substantially no flowable oxide. In other embodiments, a smallamount of flowable oxide film may remain, filling e.g., less than tenpercent by volume of the gap. As shown in FIG. 2B at 270, a small amountof top hat HDP oxide deposition may be present, however, because of theprevious one or more etch operations 209, the top hats are significantlysmaller than they otherwise would be. Moreover, the features areprotected during these etch operations. In certain embodiments, the onlyetch operations performed are those depicted in operations 209 and 213.After completing gap fill, the top of the gap and features may beplanarized, e.g., in a chemical-mechanical planarization (CMP) process(219).

FIG. 3A is a process flow diagram showing certain operations in a methodof gap fill in which flowable oxide increases bottom up fill, with theflowable oxide encapsulated by the HDP oxide, so that the flowable oxidedoes not touch the sidewalls and bottoms of gaps, and is not exposed onsurface. The process begins by providing a substrate having raisedfeatures and unfilled gaps between the raised features to an HDP-CVDreactor (301). One or more HDP-CVD deposition operations may then beperformed to partially fill the gap with HDP oxide dielectric material(303). As with the process described above with reference to FIG. 2A, ifmultiple deposition operations are to be performed, in certainembodiments, they may be interspersed with one or more intervening etchoperations and/or an etch operation may be performed after the one ormore HDP-CVD deposition operations, e.g. to remove cusp material. Incertain embodiments, however, no etch operations are performed prior tothe flowable oxide deposition. The next operation involves depositingflowable oxide film to further fill the gap (305). After the depositionof flowable oxide film, the gap is still only partially filled incertain embodiments, that is, the flowable oxide is deposited to a pointbelow the top surface of the adjacent features. This is depicted in FIG.3B, which depicts features and gaps at various stages of a process asdescribed in FIG. 3A. As with all examples described herein, theflowable oxide deposition may occur in the HDP-CVD deposition chamber orin a separate deposition chamber according to various embodiments. Theflowable oxide film is then optionally cured (307). As described aboveand detailed further below, the cure process may convert all or part ofthe film to a Si—O network. The film may be wholly or partiallysolidified by a cure process. In certain embodiments, the film isuncured prior to the subsequent HDP oxide deposition. One or moreadditional HDP-CVD depositions are performed to complete fill of the gapwith HDP oxide (309). In certain cases, the HDP-CVD process may densifythe flowable oxide film and may wholly or partially solidify it. Theresulting gap is filled with HDP oxide and flowable oxide. In certainembodiments, the HDP oxide encapsulates the flowable oxide such that theflowable oxide does not contact the sidewalls and bottoms of gaps, andis not exposed on surface of the filled gap. In alternate embodiments,the HDP oxide partially encapsulates the flowable oxide, for example,contacting the sidewalls of the gap only. After completing gap fill, thetop of the gap and features may be planarized, e.g., in achemical-mechanical planarization (CMP) process (319).

FIG. 3B depicts cross-sectional schematics of deposition in narrowtrenches, as well as in a wide trench, as described in FIG. 3A. At 320,narrow gaps 104 are depicted partially filled with HDP oxide 112,including top hat 221 and cusp 223 deposition as well as bottom-up fill.At 330, flowable oxide deposition 110 to a level below the top surfaceof the adjacent features is depicted. At 340, subsequent HDP deposition112 is depicted. At 350, FIG. 3B also shows deposition in a wide trench114. In certain embodiments in which high AR gaps are filled next tosuch a trench 114 by the method shown in FIG. 3A, the thickness offlowable oxide deposited in the trench during operation 305 is verysmall and may be negligible. Accordingly, as depicted in FIG. 3B, thetrench is substantially filled completely with HDP oxide, with nosignificant amount of flowable oxide deposited therein.

FIG. 4A is a process flow diagram illustrating another embodiment inwhich flowable oxide film increases bottom up fill. The process beginsby providing a substrate having raised features and unfilled gapsbetween the raised features to a HDP-CVD reactor (401). One or moreHDP-CVD deposition operations are then performed to partially fill thegap with HDP oxide dielectric material (403) as in the methods describedin FIGS. 2A and 3A. The next operation involves depositing flowableoxide film to overfill the gap (405), also as described above withrespect to FIG. 2A. Once the flowable oxide is deposited, an optionalcure operation may be performed (407), which may be used to tune etchcharacteristics of the deposited flowable oxide. In certain embodiments,the flowable oxide film is left uncured to exploit the differences inetch properties of the as-deposited HDP oxide and as-deposited flowableoxide films. A portion of the flowable oxide film is then selectivelyremoved, with the etchback stopping at a point below the gap opening,leaving the gap partially filled with HDP oxide and flowable oxide(409). In certain embodiments, a non-selective etch of the HDP oxide andflowable oxide is performed prior to the selective removal, with thenon-selective etchback stopping above the raised features and the gapopenings, removing at least a portion of the top hat HDP oxidedeposition. After the selective removal, all or part of the remainingflowable oxide film is optionally cured (411). As with the otherembodiments, multiple cycles of all or part of the described operationsmay be performed in certain embodiments. One or more additional HDP-CVDdepositions are performed to complete fill of the gap with HDP oxide(413). In certain embodiments wherein multiple depositions areperformed, intervening etch operations may be performed. The resultinggap is filled with HDP oxide and flowable oxide. After completing gapfill, the top of the gap and features may be planarized, e.g., in achemical-mechanical planarization (CMP) process (415).

FIG. 4B which depicts features and gaps at various stages of a processas described in FIG. 4A. At 420, narrow gaps 104 are depicted partiallyfilled with HDP oxide 112, including top hat 221 and cusp 223 depositionas well as bottom-up fill. At 430, flowable material 110 overfills thegaps with the etched back flowable film depicted at 440. Complete fillof the narrow gaps with a combination of HDP oxide 112 flowable oxide110 is depicted at 450. Deposition in a wide gap is depicted at 460.

In certain embodiments, this process scheme provides a more uniformflowable oxide height across gaps than the process scheme described inFIGS. 3A and 3B. Also, in comparison to that process scheme, the totalHDP thickness deposited in this scheme is less in certain embodiments.As a result, the CMP process is easier. As shown in FIG. 4B, theflowable oxide deposition is thicker in smaller gaps and thinner inwider gaps. Note that because at least the high AR gaps are overfilled,the amount of flowable oxide deposited in the wide gaps is greater thanthat depicted in FIG. 3B. In certain embodiments, the HDP oxideencapsulates the flowable oxide such that the flowable oxide does notcontact the sidewalls and bottoms of gaps, and is not exposed on surfaceof the filled gap. In alternate embodiments, the HDP oxide partiallyencapsulates the flowable oxide, for example, contacting the sidewallsof the gap only.

FIG. 5A is a process flow diagram illustrating an embodiment in whichflowable oxide film is used for bottom up fill with HDP oxide used as acap layer to complete fill. The process begins by providing a substratehaving raised features and unfilled gaps between the raised features toa reactor (501). Unlike the other examples, HDP oxide is not initiallyused to partially fill the unfilled gap. Rather, one or more flowableoxide depositions are performed to partially fill the gap with flowableoxide dielectric material (503). If multiple deposition operations areto be performed, in certain embodiments, they may be interspersed withone or more intervening cure operations. As with all examples describedherein, the flowable oxide deposition may occur in a HDP-CVD depositionchamber or in a separate deposition chamber according to variousembodiments. The flowable oxide film is then optionally cured (505). Thefilm may be wholly or partially solidified by a cure process. In certainembodiments, the film is uncured prior to the subsequent HDP oxidedeposition. One or more additional HDP-CVD depositions are performed tocomplete fill of the gap with HDP oxide (507). In certain cases, theHDP-CVD process may densify the flowable oxide film and may wholly orpartially solidify it. The resulting gap is filled with HDP oxide andflowable oxide, with only the HDP oxide exposed at the surface. Aftercompleting gap fill, the top of the gap and features may be planarized,e.g., in a chemical-mechanical planarization (CMP) process (509). FIG.5B depicts features and gaps at various stages of a process as describedin this example. At 520, flowable oxide deposition 110 is depicted ingaps 104. At 530, HDP oxide deposition 112 to cap the flowable oxidedeposition is depicted. And, at 540, HDP deposition 112 in a wide gap isdepicted. As with the process depicted in FIG. 3B, because there is nooverfill operation of flowable oxide, the flowable oxide thickness in awide gap (trench) is much smaller and may be negligible in certainembodiments.

In certain embodiments, flowable dielectric material is deposited in anincoming unfilled gap to reduce the aspect ratio of the gap forsubsequent fill with HDP oxide. FIG. 6A schematically depicts across-section of gaps of various aspect ratios partially filled withflowable oxide 110. The aspect ratio is defined as the depth of thetrench or other gap divided by the width of its opening. As depictedqualitatively in FIG. 6A, the aspect ratio decreases after bottom-upfill with flowable oxide. Also in FIG. 6A is a plot illustrating aspectratios prior to and after partial fill by flowable oxide for variouscritical dimensions. Critical dimension refers to the narrowestdimension of the gap opening. Gap aspect ratios as high as 14:1 werereduced to about 4:1. HDP deposition improves dramatically as aspectratios are reduced. According to various embodiments, the methodsdescribed herein may be used to fill gaps having aspect ratios as highas 60:1, e.g., about 30:1, about 20:1 or about 10:1. Critical dimensionsmay be as low as 10 nm, 15 nm or 22 nm. In certain embodiments, flowableoxide is deposited to height such that the aspect ratio of the partiallyfilled feature is about 6:1 or lower prior to HDP deposition. FIG. 6B isanother plot providing aspect ratios before and after HDP (white squarepre-flowable, and black diamonds, post flowable.) In certainembodiments, gaps of different incoming AR are partially filled with adeposition process, with the height of flowable oxide greatest for thenarrowest features.

HDP-CVD Processes

As described above, the gap fill methods according to the embodimentsdescribed herein include one or more operations in which the gap ispartially filled with a dielectric (HDP oxide) deposited by high densityplasma (HDP) chemical vapor deposition (CVD) process. Generally, a highdensity plasma is any plasma having electron density of at least about5×10¹⁰ electrons per cubic centimeter. Typically, though notnecessarily, high density plasma reactors operate at relatively lowpressures, in the range of 100 mTorr or lower. The HDP CVD depositionresults in beneficial filling of the gap from the bottom up.

Any suitable deposition chemistry may be used. In general, an HDP CVDprocess gas will include a precursor for the deposition layer. If thedielectric is a silicon-containing dielectric, then the process gas willinclude a silicon-bearing compound such as silane. The process gas willalso generally include a carrier gas. The carrier gas may be an inertgas, such as He and/or other noble gases. Or the carrier gas may be orinclude elemental or molecular hydrogen. Oxygen to form the siliconoxide or other dielectric material may be provided by thesilicon-containing precursor itself or from another process gas such aselemental oxygen (O₂), nitric oxide (NO), and/or nitrous oxide (N₂O).

The deposition process gas will have a particular compositionrepresented by flow rates of the constituent gases in units of standardcubic centimeter per minute (sccm). The process gas will include aprecursor for the deposition layer. If the dielectric is asilicon-containing dielectric, then the process gas will include asilicon-bearing compound such as SiH₄, SiF₄, Si₂H₆, TEOS (tetraethylorthosilicate), TMCTS (tetramethyl-cyclotetrasiloxane), OMCTS(octamethyl-cyclotetrasiloxane), methyl-silane, dimethyl-silane, 3MS(trimethylsilane), 4MS (tetramethylsilane), TMDSO(tetramethyl-disiloxane), TMDDSO (tetramethyl-diethoxyl-disiloxane),DMDMS (dimethyl-dimethoxyl-silane) and mixtures thereof. Duringdeposition, the process decomposes the silicon-containing reactant toform a silicon-containing gas and plasma phase species, which can reacton the surface of the substrate.

The process gas will also generally include a carrier gas. The carriergas may be an inert gas, such as He and/or other noble gases, e.g., Ar.Or the carrier gas may be or include elemental or molecular hydrogen.

Example flow rate ranges for process gases of the present invention arelisted below.

Gas Flow Rate (sccm) SiH₄ 10-300  O₂ 20-1000 He 0-500 H₂  0-5000 Ar0-500

Generally, other oxygen and silicon-containing compounds can besubstituted for those listed in this table. Depending upon the atomcounts in the precursor gases, the flow rate ranges may have to bechanged. While there are no precise rules for modifying flow rates as afunction of molecular structure, generally the flow rate of thesilicon-containing precursor may be reduced by a factor corresponding tothe number of silicon atoms in the molecule. HDP-CVD process gases maycontain noble gases (e.g., argon, helium, or xenon) either as the solecarrier gas, or in a mixture with hydrogen.

For doped dielectrics (particularly silicon dioxide based dielectrics),the process gas may include a dopant precursor such as aboron-containing gas, a phosphorus-containing gas, a carbon-containinggas, or a mixture thereof. In a specific embodiment, the gas includesone or more boron-containing reactants and one or morephosphorus-containing reactants and the dielectric film includes aphosphorus- and boron-doped silicon oxide glass (BPSG). Examples ofsuitable boron and phosphorus precursor gases include the following:B₂H₆ and PH₃.

If the dielectric is to contain an oxyfluoride (e.g., siliconoxyfluoride), then the process gas preferably includes afluorine-containing reactant such as silicon hexafluoride (SiF₄). If thedielectric is to contain an oxynitride (e.g., silicon oxynitride), thenthe process gas preferably includes a nitrogen-containing reactant suchas N₂, NH₃, NF₃, NO, N₂O, and mixtures thereof.

The method applies as well to the deposition (biased or unbiased) ofcarbon-doped silicon oxide from process gas mixtures includingorganosilanes (e.g., TEOS (tetraethyl orthosilicate), TMCTS(tetramethyl-cyclotetrasiloxane), OMCTS (octamethyl-cyclotetrasiloxane),methyl-silane, dimethyl-silane, 3MS (trimethylsilane), 4MS(tetramethylsilane), TMDSO (tetramethyl-disiloxane), TMDDSO(tetramethyl-diethoxyl-disiloxane), DMDMS (dimethyl-dimethoxyl-silane)and mixtures thereof).

Reactor pressure is held at a value necessary to sustain thehigh-density plasma. In certain embodiments the process vessel ismaintained at a pressure of at most about 100 mTorr. In some cases, theprocess chamber pressure is maintained below 1 mTorr. For manyapplications, however, the pressure is maintained between about 1 and100 mTorr; most preferably between about 1 and 30 mTorr.

The temperature within the process vessel should be maintainedsufficiently high to ensure that the dielectric deposition reactionproceeds efficiently. Hence, the temperature preferably resides atvalues between about 30 and 1000° C. This temperature will varydepending upon the types of precursors employed in the reaction.Further, the temperature may be limited by process constraints, such asthermal budget limitations that preclude temperatures above 700-750° C.Such constraints become increasingly common with advanced technologiesand corresponding smaller feature sizes. For such applications, theprocess temperature may be maintained between about 30 and 750° C.

As indicated, to control the substrate temperature, the reactor maysupply a heat transfer gas between a surface of the substrate and asurface of the substrate holder on which the substrate is supportedduring film deposition. The heat transfer gas may include at least oneof helium and argon. The back-side helium pressure is set by thetemperature requirements of the process (a typical range being between0-15 Torr).

For some applications, it may be desirable to preheat the wafer to apre-specified relatively low temperature and then gradually raise thetemperature. This allows for isothermal operation. The goal is to startthe deposition and then maintain the wafer temperature within a narrowrange during the entire deposition process.

The low frequency power applied to the upper electrode (for generatingthe plasma) typically varies from 1 kW to 20 kW, and the high frequencypower (for biasing the wafer) typically reaches at least about 0.2 W/cm²(preferably varying from about 0.5 kW to 10 kW) depending on thesubstrate size (e.g., 200 or 300 mm diameter) and the requirements ofthe specific process being used.

As indicated above, the bias applied to the substrate is typically aradio frequency bias. Applying radio frequency bias to the substrateinvolves supporting the substrate on a substrate holder having anelectrode supplying a radio frequency bias to the substrate. For manyembodiments, the radio frequency bias applied to the substrate is at thefrequency range of between about 100 kHz and 27 MHz. The frequency rangeapplied to the upper, plasma-generating electrode is typically betweenabout 300 kHz and 27 MHz.

The deposition conditions may be selected to optimize depositiontopography. The deposition topography can be optimized by manipulatingthe S/D ratio of the deposition process. S/D ratio refers to thesputter/deposition ratio. It is obtained by measuring the depositionrate for a given dielectric deposition process and then measuring thesputter rate for that same process performed without thesilicon-containing precursor (e.g., silane). The S/D ratio is given bythe following expression:

-   -   S/D=sputter rate/(sputter rate+deposition rate).

The conditions may be set so that the isotropic etch is selective forthe HDP CVD deposited dielectric (e.g., SiO₂) relative to the featurematerial, e.g., a silicon nitride barrier layer lining the gap.

An HDP deposition operation may include only a single deposition, or asingle deposition-etch operation, or may include a multipledeposition-etch cycles. For example, multiple SiH₄/O₂ depositionoperations may include intervening NF₃ plasma etch operations.

While the above provides a description of example HDP-CVD processes andconditions, the methods described herein are not limited to theseparticular HDP-CVD processes but may be applied with other HDP-CVDprocesses.

Flowable Oxide Deposition Processes

As described above, the gap fill methods according to the embodimentsdescribed herein include one or more operations in which the gap ispartially filled or overfilled with a dielectric flowable oxide film. Inmany embodiments, the flowable dielectric film is a flowable silicon andoxygen-containing film, though the integration schemes described hereincan also be implemented with other flowable dielectric films. Accordingto various embodiments, the flowable film is formed by a spin-on glasstechnique. In alternate embodiments, the flowable film is formed byintroducing vapor phase reactants to a deposition chamber at conditionssuch that a flowable film is formed on the substrate to fill the gap.

After the substrate is provided to the reaction chamber, process gasesare introduced. For forming silicon oxides, the process gas reactantsgenerally include a silicon-containing compound and an oxidant, and mayalso include a catalyst, a solvent and other additives. The gases mayalso include one or more dopant precursors, e.g., a fluorine,phosphorous and/or boron-containing gas. Sometimes, though notnecessarily, an inert carrier gas is present. In certain embodiments,the gases are introduced using a liquid injection system. In certainembodiments, the silicon-containing compound and the oxidant areintroduced via separate inlets or are combined just prior tointroduction into the reactor in a mixing bowl and/or showerhead. Thecatalyst and/or optional dopant may be incorporated into one of thereactants, pre-mixed with one of the reactants or introduced as aseparate reactant. The substrate is then exposed to the process gases atan operation. Conditions in the reactor are such that thesilicon-containing compound and the oxidant react to form a condensedflowable film on the substrate. Formation of the film may be aided bypresence of a catalyst. The method is not limited to a particularreaction mechanism, e.g., the reaction mechanism may involve acondensation reaction, a vapor-phase reaction producing a vapor-phaseproduct that condenses, condensation of one or more of the reactantsprior to reaction, or a combination of these. The substrate is exposedto the process gases for a period sufficient to deposit a flowable filmto fill at least some of the gap or overfill the gap as desired.

In certain embodiments, the overall deposition process may be describedin context of two steps: hydrolysis and condensation. The first stepinvolves hydrolysis of silicon-containing precursors by the oxidant. Forexample, alkoxy groups (—OR) of the silicon containing precursor may bereplaced with hydroxyl groups (—OH). In the condensation step, Si—O—Silinkages may be formed when —OH groups are removed from Si. It should benoted that while these reaction steps provide a useful framework fordescribing various aspects of the invention, the methods describedherein are not necessarily limited to a particular reaction mechanism.

FIG. 7 provides certain operations in a method of filling a gap with aflowable oxide material according to certain embodiments. The processtypically begins prior to any oxide material being deposited in the gap,with the gap defined by sidewall and bottom surfaces. The sidewall andbottom surfaces may be silicon nitride, silicon oxide, siliconoxynitride, or other silicon-containing materials.

At 701, a substrate including a gap is provided. Then an optionalpretreatment operation is performed (Block 703). According to variousembodiments, a pretreatment operation involves exposure to a plasmacontaining oxygen, nitrogen, helium or some combination of these. Theplasma may be downstream or in-situ, generated by a remote plasmagenerator, such as an Astron® remote plasma source, aninductively-coupled plasma generator or a capacitively-coupled plasmagenerator. Examples of pre-treatment gases include O₂, O₃, H₂O, NO, NO₂,N₂O, H₂, N₂, He, Ar, and combinations thereof, either alone or incombination with other compounds. Examples of chemistries include O₂,O₂/N₂, O₂/He, O₂/Ar, O₂/H₂. The particular process conditions may varydepending on the implementation. In alternate embodiments, thepretreatment operation involves exposing the substrate to O₂, O₂/N₂,O₂/He, O₂/Ar or other pretreatment chemistries, in a non-plasmaenvironment. In these embodiments, the substrate may be exposed to thepretreatment chemistry in the presence energy from another energysource, including a thermal energy source, a ultra-violet source, amicrowave source, etc. In certain embodiments, other pretreatmentoperations described above, a substrate is pretreated with exposure to acatalyst. The pre-treatment operation, if performed, may occur in thedeposition chamber or may occur in another chamber prior to transfer ofthe substrate to the deposition chamber. Once in the deposition chamber,and after the optional pre-treatment operation, process gases areintroduced.

Deposition Chemistries

For forming silicon oxides, the process gas reactants generally includea silicon-containing compound and an oxidant, and may also include acatalyst, a solvent and other additives. The gases may also include oneor more dopant precursors, e.g., a fluorine, phosphorous and/orboron-containing gas. Sometimes, though not necessarily, an inertcarrier gas is present. In certain embodiments, the gases are introducedusing a liquid injection system. In certain embodiments, thesilicon-containing compound and the oxidant are introduced via separateinlets or are combined just prior to introduction into the reactor in amixing bowl and/or showerhead. The catalyst and/or optional dopant maybe incorporated into one of the reactants, pre-mixed with one of thereactants or introduced as a separate reactant. The substrate is thenexposed to the process gases to deposit a flowable film in the gap at anoperation 705. Conditions in the reactor are such that thesilicon-containing compound and the oxidant react to form a condensedflowable film on the substrate. Formation of the film may be aided bypresence of a catalyst. The method is not limited to a particularreaction mechanism, e.g., the reaction mechanism may involve acondensation reaction, a vapor-phase reaction producing a vapor-phaseproduct that condenses, condensation of one or more of the reactantsprior to reaction, or a combination of these. The substrate is exposedto the process gases for a period sufficient to deposit a flowable filmto fill at least some of the gap or overfill the gap as desired.

In certain embodiments, the silicon-containing precursor is analkoxysilane. Alkoxysilanes that may be used include, but are notlimited to, the following:

H_(x)—Si—(OR)_(y) where x=0-3, x+y=4 and R is a substituted orunsubstituted alkyl group;R′_(x)—Si—(OR)_(y) where x=0-3, x+y=4, R is a substituted orunsubstituted alkyl group and R′ is a substituted or unsubstitutedalkyl, alkoxy or alkoxyalkane group; andH_(x)(RO)_(y)—Si—Si—(OR)_(y)H_(x) where x=0-2, x+y=0-2 and R is asubstituted or unsubstituted alkyl group.

Examples of silicon containing precursors include, but are not limitedto, alkoxysilanes, e.g., tetraoxymethylcyclotetrasiloxane (TOMCTS),octamethylcyclotetrasiloxane (OMCTS), tetraethoxysilane (TEOS),triethoxysilane (TES), trimethoxysilane (TriMOS),methyltriethoxyorthosilicate (MTEOS), tetramethylorthosilicate (TMOS),methyltrimethoxysilane (MTMOS), dimethyldimethoxysilane (DMDMOS),diethoxysilane (DES), dimethoxysilane (DMOS), triphenylethoxysilane,1-(triethoxysilyl)-2-(diethoxymethylsilyl)ethane, tri-t-butoxylsilanol,hexamethoxydisilane (HMODS), hexaethoxydisilane (HEODS),tetraisocyanatesilane (TICS), and bis-tert-butylamino silane (BTBAS).Further examples of silicon containing precursors include silane (SiH₄)and alkylsilanes, e.g., methylsilane, and ethylsilane.

In certain embodiments, carbon-doped precursors are used, either inaddition to another precursor (e.g., as a dopant) or alone. Carbon-dopedprecursors include at least one Si—C bond. Carbon-doped precursors thatmay be used include, but are not limited to the, following:

R′_(x)—Si—R_(y) where x=0-3, x+y=4, R is a substituted or unsubstitutedalkyl group and R′ is a substituted or unsubstituted alkyl, alkoxy oralkoxyalkane group; andSiH_(x)R′_(y)—R_(z) where x=1-3, y=0-2, x+y+z=4, R is a substituted orunsubstituted alkyl group and R′ is a substituted or unsubstitutedalkyl, alkoxy or alkoxyalkane group.

Examples of carbon-doped precursors include (CH₃Si(OCH₂)₃,trimethylsilane (3MS), tetramethylsilane (4MS), diethoxymethylsilane(DEMS), dimethyldimethoxysilane (DMDMOS), methyl-triethoxysilane (MTES),methyl-trimethoxysilane, methyl-diethoxysilane andmethyl-dimethoxysilane. Additional carbon-doped precursors are describedabove. In certain embodiments, the film is doped with extra silicon.

Examples of suitable oxidants include, but are not limited to, ozone(O₃), peroxides including hydrogen peroxide (H₂O₂), oxygen (O₂), water(H₂O), alcohols such as methanol, ethanol, and isopropanol, nitric oxide(NO), nitrous dioxide (NO₂) nitrous oxide (N₂O), carbon monoxide (CO)and carbon dioxide (CO₂). In certain embodiments, a remote plasmagenerator may supply activated oxidant species.

One or more dopant precursors, catalysts, inhibitors, buffers, solventsand other compounds may be introduced. In certain embodiments, a protondonor catalyst is employed. Examples of proton donor catalystsinclude 1) acids including nitric, hydrofluoric, phosphoric, sulphuric,hydrochloric and bromic acids; 2) carboxylic acid derivatives includingR—COOH and R—C(═O)X where R is substituted or unsubstituted alkyl, aryl,acetyl or phenol and X is a halide, as well as R—COOC—R carboxylicanhydrides; 3) Si_(x)X_(y)H_(z) where x=1-2, y=1-3, z=1-3 and X is ahalide; 4) R_(x)Si—X_(y) where x=1-3 and y=1-3; R is alkyl, aloxy,aloxyalkane, aryl, acetyl or phenol; and X is a halide; and 5) ammoniaand derivatives including ammonium hydroxide, hydrazine, hydroxylamine,and R—NH₂ where R is substituted or unsubstituted alkyl, aryl, acetyl,or phenol.

In addition to the examples of catalysts given above, halogen-containingcompounds which may be used include halogenated organic molecule such asdichlorosilane (SiCl₂H₂), trichlorosilane (SiCl₃H), methylchlorosilane(SiCH₃ClH₂), chlorotriethoxysilane, and chlorotrimethoxysilane. Acidswhich may be used may be mineral acids such as hydrochloric acid (HCl),sulphuric acid (H₂SO₄), and phosphoric acid (H₃PO₄); organic acids suchas formic acid (HCOOH), acetic acid (CH3COOH), and trifluoroacetic acid(CF₃COOH). Bases which may be used include ammonia (NH3) or ammoniumhydroxide (NH₄OH), phosphine (PH₃); and other nitrogen- orphosphorus-containing organic compounds. Additional examples ofcatalysts are chloro-diethoxysilane, methanesulfonic acid (CH₃SO₃H),trifluoromethanesulfonic acid (“triflic”, CF₃SO₃H),chloro-dimethoxysilane, pyridine, acetyl chloride, chloroacetic acid(CH₂ClCO₂H), dichloroacetic acid (CHCl₂CO₂H), trichloroacetic acid(CCL₂CO₂H), oxalic acid (HO₂CCO₂H) and benzoic acid (C₆H₅CO₂H).

According to various embodiments, catalysts and other reactants may beintroduced simultaneously or in particular sequences. For example, insome embodiments, a acidic compound may be introduced into the reactorto catalyze the hydrolysis reaction at the beginning of the depositionprocess, then a basic compound may be introduced near the end of thehydrolysis step to inhibit the hydrolysis reaction and the catalyze thecondensation reaction. Acids or bases may be introduced by normaldelivery or by rapid delivery or “puffing” to catalyze or inhibithydrolysis or condensation reaction quickly during the depositionprocess. Adjusting and altering the pH by puffing may occur at any timeduring the deposition process, and difference process timing andsequence may result in different films with properties desirable fordifferent applications. Some examples of catalysts are given above.Examples of other catalysts include hydrochloric acid (HCl),hydrofluoric acid (HF), acetic acid, trifluoroacetic acid, formic acid,dichlorosilane, trichlorosilane, methyltrichlorosilane,ethyltrichlorosilane, trimethoxychlorosilane, and triethoxychlorosilane.Methods of rapid delivery that may be employed are described in U.S.application Ser. No. 12/566,085, incorporated by reference herein. Incertain embodiments, a multistage flowable oxide deposition isperformed, in which the presence, identity or amount of catalyst isvaried according to if a gap is being filled, or a planar or overburdenlayer is deposited. For example, features are selectively filled by anuncatalyzed process, and an overburden or blanket layer is depositedusing a catalyst.

Solvents may be non-polar or polar and protic or aprotic. The solventmay be matched to the choice of dielectric precursor to improve themiscibility in the oxidant. Non-polar solvents include alkanes andalkenes; polar aprotic solvents include acetones and acetates; and polarprotic solvents include alcohols and carboxylic compounds.

Examples of solvents that may be introduced include alcohols, e.g.,isopropyl alcohol, ethanol and methanol, or other compounds, such asethers, carbonyls, nitriles, miscible with the reactants. Solvents areoptional and in certain embodiments may be introduced separately or withthe oxidant or another process gas. Examples of solvents include, butnot limited to, methanol, ethanol, isopropanol, acetone, diethylether,acetonitrile, dimethylformamide, and dimethyl sulfoxide, tetrahydrofuran(THF), dichloromethane, hexane, benzene, toluene, isoheptane anddiethylether. The solvent may be introduced prior to the other reactantsin certain embodiments, either by puffing or normal delivery. In someembodiments, the solvent may be introduced by puffing it into thereactor to promote hydrolysis, especially in cases where the precursorand the oxidant have low miscibility.

Sometimes, though not necessarily, an inert carrier gas is present. Forexample, nitrogen, helium, and/or argon, may be introduced into thechamber with one of the compounds described above.

As indicated above, any of the reactants (silicon-containing precursor,oxidant, solvent, catalyst, etc.) either alone or in combination withone or more other reactants, may be introduced prior to the remainingreactants. Also in certain embodiments, one or more reactants maycontinue to flow into the reaction chamber after the remaining reactantflows have been shut off.

In certain embodiments, reactions conditions are such that thesilicon-containing compound and oxidant, undergo a condensationreaction, condensing on the substrate surface to form a flowable film.In certain embodiments, the reaction takes place in dark or non-plasmaconditions. In other embodiments, the reaction takes place in thepresence of a plasma. Methods of depositing a flowable film for gap fillvia a plasma-enhanced chemical vapor deposition (PECVD) reaction aredescribed in U.S. patent application Ser. No. 12/334,726, incorporatedby reference herein.

Chamber pressure may be between about 1-200 Torr, in certainembodiments, it is between 10 and 75 Torr. In a particular embodiment,chamber pressure is about 10 Torr.

Partial pressures of the process gas components may be characterized interms of component vapor pressure and range as follows, with Pp thepartial pressure of the reactant and Pvp the vapor pressure of thereactant at the reaction temperature:

Precursor partial pressure ratio (Pp/Pvp)=0.01-1, e.g., 0.01-0.5Oxidant partial pressure ratio (Pp/Pvp)=0.25-2, e.g., 0.5-1Solvent partial pressure ratio (Pp/Pvp)=0-1, e.g., 0.1-1

In certain embodiments, the process gas is characterized by having aprecursor partial pressure ratio is 0.01 and 0.5, an oxidant partialratio between 0.5 and 1, and a solvent (if present) partial pressureratio between 0.1 and 1. In the same or other embodiments, the processgas is characterized by the following:

Oxidant:Precursor partial pressure ratio(Pp_(oxidant)/Pp_(precursor))=1-30, e.g., 5-15Solvent:Oxidant partial pressure ratio (Pp_(solvent)/Pp_(oxidant))=0-10,e.g., 0.1-5

In certain embodiments, the process gas is characterized by anoxidant:precursor partial pressure ratio of between about 5 and 15 and asolvent:oxidant partial pressure ratio of between about 0.1 and 5; aswell as further characterized by the ratios described above.

Substrate temperature is between about −20° C. and 100° C. in certainembodiments. In certain embodiments, temperature is between about −20°C. and 30° C., e.g., between −10° C. and 10° C. Pressure and temperaturemay be varied to adjust deposition time; high pressure and lowtemperature are generally favorable for quick deposition. Hightemperature and low pressure will result in slower deposition time.Thus, increasing temperature may require increased pressure. In oneembodiment, the temperature is about 5° C. and the pressure about 10Torr. Exposure time depends on reaction conditions as well as thedesired film thickness. Deposition rates are from about 100angstroms/min to 1 micrometer/min according to various embodiments. Incertain embodiments, deposition time is 0.1-180 seconds, e.g., 1-90seconds. In certain embodiments, deposition time is less than nucleationdelay for the same deposition process on a blanket film.

The substrate is exposed to the reactants under these conditions for aperiod long enough to deposit a flowable film in the gap. In thedepicted embodiment, the entire desired thickness of film is depositedin operation 705, as it is a single cycle deposition. In otherembodiments which employ multiple deposition operations, only a portionof the desired film thickness is deposited in a particular cycle. Incertain embodiments, the substrate is continuously exposed to thereactants during operation 705, though in other embodiments, one or moreof the reactants may be pulsed or otherwise intermittently introduced.Also as noted above, in certain embodiments, one or more of thereactants including a dielectric precursor, oxidant, catalyst orsolvent, may be introduced prior to introduction of the remainingreactants and/or continue flowing into the reactor after the remainingreactant flows are shut off.

Exposure time depends on reaction conditions as well as the desired filmthickness. Deposition rates are typically from about 100 angstroms/minto 1 micrometer/min. In certain embodiments, the deposition may be aplasma-enhanced chemical vapor deposition (PECVD) reaction that uses acapacitively-coupled plasma source. PECVD reactions have lower plasmadensities than HDP plasmas, e.g., 10⁸ electrons/cm³ and up to 10¹⁰electrons/cm³.

Post-Deposition Treatments

After deposition, the as-deposited film is treated according to variousembodiments (Block 707). According to various embodiments, one or moretreatment operations are performed to do one or more of the following:introduction of a dopant, chemical conversion of the as-deposited film,and densification. In certain embodiments, a single treatment may do ormore of these. A post-deposition treatment may be performed in situ,i.e., in the deposition chamber, or in another chamber. Densificationoperations may be plasma-based, purely thermal, or by exposure toradiation such as ultra-violet, infra-read or microwave radiation.

Post-deposition treating of the flowable oxide film, if performed, maybe done in situ or ex situ of the deposition chamber. Thepost-deposition densification treatment operation may involve one ormore operations, any or all of which may also result in chemicallyconverting the as-deposited film. In other embodiments, any or all ofthe densification operations may densify without conversion. In certainembodiments, one conversion operation may be separately performed, ornot performed at all. If separately performed, a conversion operationmay be performed before or after a densification operation. In oneexample, a film is converted and partially densified by exposure to areactive plasma followed by further densification by thermal anneal inan inert environment.

According to various embodiments, the film may be densified by purelythermal anneal, exposure to a plasma, exposure to ultraviolet ormicrowave radiation or exposure to another energy source. Thermal annealtemperatures may be 300 C or greater (depending on thermal budget). Thetreatment may be performed in an inert environment (Ar, He, etc.) or ina potentially reactive environment. Oxidizing environments (using O₂,N₂O, O₃, H₂O, H₂O₂, NO, NO₂, CO, CO₂ etc.) may be used, though incertain situation nitrogen-containing compounds will be avoided toprevent incorporation of nitrogen in the film. In other embodiments,nitridizing environments (using N₂, N₂O, NH₃, NO, NO₂ etc.) are used. Insome embodiments, a mix of oxidizing and nitridizing environments areused. Carbon-containing chemistries may be used to incorporate someamount of carbon into the deposited film. According to variousembodiments, the composition of the densified film depends on theas-deposited film composition and the treatment chemistry. For example,in certain embodiments, an Si(OH)x as-deposited gel is converted to aSiO network using an oxidizing plasma cure. In other embodiments, aSi(OH)x as-deposited gel is converted to a SiON network.

In certain embodiments, the film is treated by exposure to a plasma,either remote or direct (inductive or capacitive). This may result in atop-down conversion of the flowable film to a densified solid film. Theplasma may be inert or reactive. Helium and argon plasma are examples ofinert plasmas; oxygen and steam plasmas are examples of oxidizingplasmas (used for example, to remove carbon as desired). Hydrogenplasmas may also be used. Temperatures during plasma exposure aretypically about 200° C. or higher. In certain embodiments, an oxygen oroxygen-containing plasma is used to remove carbon.

Temperatures may range from 0-600° C., with the upper end of thetemperature range determined by the thermal budget at the particularprocessing stage. For example, in certain embodiments, the entireprocess shown in FIG. 3 is carried out at temperatures less than about400° C. This temperature regime is compatible with NiSi contacts. Incertain embodiments, the temperatures range from about 200° C.-550° C.Pressures may be from 0.1-10 Torr, with high oxidant pressures used forremoving carbon.

Other annealing processes, including rapid thermal processing (RTP) mayalso be used to solidify and shrink the film. If using an ex situprocess, higher temperatures and other sources of energy may beemployed. Ex situ treatments include high temperature anneals (700-1000°C.) in an environment such as N₂, O₂, H₂O and He. In certainembodiments, an ex situ treatment involves exposing the film toultra-violet radiation, e.g., in a ultraviolet thermal processing (UVTP)process. For example, temperatures of 400° C. or above in conjunctionwith UV exposure may be used to cure the film. Other flash curingprocesses, including RTP, may be used for the ex situ treatment as well.

In certain embodiments, a film is densified and converted by the sameprocess operations. Converting a film involves using a reactivechemistry. According to various embodiments, the composition of the filmdepends on the as-deposited film composition and the cure chemistry. Forexample, in certain embodiments, an Si(OH)x as-deposited gel isconverted to a SiO network using an oxidizing plasma cure. In otherembodiments, a Si(OH)x as-deposited gel is converted to a SiON networkby exposure to an oxidizing and nitridizing plasma.

In other embodiments, the flowable dielectric film may be a silicon andnitrogen-containing film, such as silicon nitride or silicon oxynitride.It may be deposited by introducing vapor phase reactants to a depositionchamber at conditions such that they react to form a flowable film. Thevapor phase reactants may include species created by a plasma. Such aplasma may be generated remotely or in the deposition chamber. Thenitrogen incorporated in the film may come from one or more sources,such as a silicon and nitrogen-containing precursor (for example,trisilylamine (TSA) or disilylamine (DSA)), a nitrogen precursor (forexample, ammonia (NH3) or hydrazine (N2H4)), or a nitrogen-containinggas fed into a plasma (N2, NH3, NO, NO2, N2O). After deposition, theflowable dielectric film may be treated to do one of more of thefollowing: chemical conversion of the as-deposited film, densification.The chemical conversion may include removing some or all of the nitrogencomponent, converting a Si(ON)x film to a primarily SiO network. It mayalso include removal of one or more of —H, —OH, —CH and —NH species fromthe film. The post-deposition treatment may include exposure to thermal,plasma, UV, IR or microwave energy.

Reaction Mechanism

As indicated above, the flowable dielectric deposition may involvevarious reaction mechanisms depending on the specific implementation.Examples of reaction mechanisms in a method of depositing a flowableoxide film according to certain embodiments are described below. Itshould be noted that while these reaction steps provide a usefulframework for describing various aspects of the invention, the methodsdescribed herein are not necessarily limited to a particular reactionmechanism.

The overall deposition process may be described in context of two steps:hydrolysis and condensation. The first step involves hydrolysis ofsilicon-containing precursors by the oxidant. For example, alkoxy groups(—OR) of the silicon containing precursor may be replaced with hydroxylgroups (—OH). The —OH groups and the residual alkoxy groups participatein condensation reactions that lead to the release of water and alcoholmolecules and the formation of Si—O—Si linkages. In this mechanism, theas-deposited film does not have appreciable carbon content even thoughthe alkoxysilane precursor contains carbon. In certain embodiments,reactant partial pressure is controlled to facilitate bottom up fill.Liquid condensation occurs below saturation pressure in narrow gaps; thereactant partial pressure controls the capillary condensation. Incertain embodiments, reactant partial pressure is set slightly below thesaturation pressure. In a hydrolyzing medium, the silicon-containingprecursor forms a fluid-like film on the wafer surface thatpreferentially deposits in trenches due to capillary condensation andsurface tension forces, resulting in a bottom-up fill process.

FIGS. 8A-8D provides a simplified schematic diagram of deposition andanneal reaction mechanisms according to one embodiment. It should benoted that the methods described herein are not limited to theparticular reactants, products and reaction mechanisms depicted, but maybe used with other reactants and reaction mechanisms that produceflowable dielectric films. It will also be understood that depositionand annealing may involve multiple different concurrent or sequentialreaction mechanisms.

FIG. 8A depicts reactant condensation, hydrolysis and initiation of theflowable film on a wafer 801, held at a reduced temperature such as −5°C. The reactants include a dielectric precursor 802, an oxidant 804, anoptional catalyst 803 and an optional solvent 805. The dielectricprecursor absorbs 802 on the surface. A liquid phase reaction betweenprecursor and oxidant results in hydrolysis of precursor, formingsilanols Si(OH)x (806) attached to the wafer surface initiating thegrowth of the film. In certain embodiments, the presence of the solventimproves miscibility and surface wettability.

FIG. 8B depicts polymerization of the product (see Si(OH)x chain 808) aswell as condensation of the silanols to form crosslinked Si—O chains.The result of the condensation reaction is a gel 809. At this stage, theorganic groups may be substantially eliminated from the gel 809, withalcohol and water released as byproducts, though as depicted Si—H groups811 remain in the gel as do hydroxyl groups. In some cases, a minute butdetectable amount of carbon groups remains in the gel. The overallcarbon content may be less than 1% (atomic). In some embodiments,essentially no carbon groups remain, such that Si—C groups areundetectable by FTIR. FIG. 8C depicts a reaction mechanism during ananneal, in this case in the presence of an activated oxygen species O*(810), e.g. oxygen radicals, ions, etc. In certain embodiments, theanneal has two effects: 1) oxidation of the gel, to convert SiOH and SiHto SiO and the gel to a SiO network 813; and 2) film densification orshrinkage. The oxygen oxidizes Si—H bonds and facilitates formation of aSiOx network with substantially no Si—H groups. The substratetemperature may be raised, e.g., to 375° C. to facilitate film shrinkageand oxidization. In other embodiments, the oxidation and shrinkageoperations are carried out separately. In some embodiments, oxidationmay occur at a first temperature (e.g., 300° C.) with furtherdensification occurring at a higher temperature (e.g., 375° C.). FIG. 8Dshows a schematic depiction of a densified SiO film 814.

Fill Height Selectivity

Flowable oxide fill height is a function of critical dimension. That is,deposition into wide features results in little to no fill height withheight increasing as the feature dimension narrows. It has been foundthat in certain embodiments, the slope of the fill height vs. criticaldimension curve is tunable by tuning reactant partial pressures. FIG. 9Apresents qualitative examples in which curve 902 is obtained by loweringthe solvent partial pressure and curve 903 is obtained by raising thesolvent partial pressure. In this manner, the fill selectivity acrossfeatures of various critical dimensions can be tuned for a particulardeposition, for example, to increase fill height in narrow features anddecrease it in wide features.

FIG. 9B is a graph showing two data series: the data points representedby a square are from a process having a higher solvent (ethanol) partialpressure; the data points represented by a diamond using the sameprocess but with lower solvent (ethanol) partial pressure. As can beseen lower solvent partial pressure changes the slope of the curve suchthat fill selectivity of narrower features is increased. Without beingbound by a particular theory, it is believed that the tunability of fillheight selectivity is a feature of depositions involving capillarycondensation mechanisms. The amount of solvent, for example, has a largeeffect on the surface tension of the fill already in the feature, andhence the capillary condensation mechanism. Ranges of reactant partialpressure ratios are provided above. Capillary condensation mechanismsaccording to certain embodiments are described above and in U.S. Pat.No. 7,074,690, incorporated by reference above.

Process Sequences

FIGS. 10-12 provide examples of process sequences according to variousembodiments. First, in FIG. 10, a process begins by pre-treating awafer, e.g., to make it hydrophilic or otherwise treated for deposition.(Block 1001). Examples of pre-treatments are described above. In someembodiments, this operation may not be performed, that is the wafer maybe provided directly to a flowable oxide deposition module fordeposition. As indicated in FIG. 10, if the pre-treatment is performedoutside the flowable oxide deposition module, the wafer is thentransferred to the flowable oxide deposition module (1003). Thistypically occurs under inert atmosphere or vacuum to preserve theeffects of the pre-treatment. One or more gaps are then partially filledwith a flowable oxide film. (Block 1005). According to variousembodiments, this may involve a single deposition, or multipledeposition cycles. If an in situ post-deposition treatment is to beperformed, it is done in the deposition module (Block 1007). After thein situ post-deposition treatment is performed, or directly afterdeposition if no in situ treatment is performed, the wafer istransferred to a separate cure module and treated if a separatetreatment is to be performed (Block 1009). For example, in certainembodiments, the wafer is transferred to a remote cure module forexposure to a remotely generated oxidizing plasma. The wafer is thentransferred to an HDP deposition module for HDP deposition. (Block1011). HDP oxide is then deposited. (Block 1013). Although notindicated, exposure to a direct inductively couple oxidizing plasma orother treatment may occur in the HDP module prior to deposition of HDPoxide in some embodiments. In some embodiments, the flowable film isoxidized during HDP oxide deposition.

Various modifications may be made in the process shown in FIG. 10. Forexample, in certain embodiments, pre-treatment and/or flowable oxidedeposition may take place in the HDP deposition module, eliminatingcertain transfer operations. It should be noted that prior to operation1001, the gaps on the wafer may be unfilled (e.g., as depicted in FIG.1A) or may be partially filled from one or more preceding flowable oxideor HDP depositions as described above.

Once in the HDP chamber, the wafer may be subjected to a pre-heatoperation. According to various embodiments, the pre-heat may beaccompanied by exposure to an oxidant to oxidize the flowable film priorto HDP oxide deposition. In other embodiments, the pre-heat is performedin an oxidant-free environment. The latter may be done, e.g., aftertreatment in a remote plasma cure module.

FIG. 11 is a process sequence according to certain embodiments in whichthe flowable dielectric material is deposited in a gap formed in asilicon or SOI surface. An example is gap fill in an STI integrationprocess. The process described in FIG. 11 may be used in conjunctionwith that described in FIG. 10, for example. First, a silicon or SOIwafer including a gap formed in the silicon or SOI is provided. (Block1101). Flowable dielectric material is then deposited in the gap. (Block1103). Various pre-treatments as described above may be performed priorto deposition. The flowable dielectric material is then selectivelyoxidized, i.e., it is oxidized without oxidizing the underlying silicon.(Block 1105).

Selectively oxidizing the flowable dielectric material may involveexposure to a remotely generated oxidizing plasma, exposure toultraviolet radiation in the presence of steam or another oxidant, orexposure to an oxidant in a thermal anneal, e.g., a steam anneal. Asdescribed above, these may be performed in the deposition chamber or inanother chamber. In certain embodiments, a direct (non-remote)inductively-coupled or capacitively-coupled oxidizing plasma is used toselectively oxidize the flowable dielectric material. In such instances,selective oxidation may involve not applying a bias to the substrateand/or performing the oxidation at relatively low temperatures. In oneexample, the plasma is applied at the deposition temperature in situ inthe chamber. Lowering plasma density may also improve selectivity. Alsoin certain embodiments, pre-heat in an HDP chamber is done in anon-oxidant environment to prevent oxidation of the underlying layer.

As mentioned above, in certain embodiments deposition of the flowabledielectric film involves multiple deposition-cure cycles. FIG. 12illustrates a process sequence involving such an operation. First, asubstrate including a gap is provided. (Block 1201). Then, an amount offlowable oxide film is deposited in the gap. (Block 1203). In certainembodiments, the amount of flowable oxide deposited in operation 1203 isless than the total desired amount of flowable oxide desired in the gap.The deposited flowable dielectric material is then treated to wholly orpartially solidify the material deposited in the previous operation.(Block 1205). Here, the treatment that is performed does not appreciablyshrink the film, but dries or solidifies it such that it providesstructural reinforcement to the sidewalls of the gap. Solidification ordrying without substantial shrinkage may be accomplished in certainembodiments by an in-situ inert or reactive plasma at the depositiontemperature or non-plasma exposure to an oxidant. While there may besome amount of cross-linking and densification, this operation isdistinct from a full densification and cross-linking. In certainembodiments, the treatment also functions as a pre-treatment for asubsequent deposition operation. In one example, the film is exposed toa nitrogen and oxygen-containing plasma at the deposition temperature.In other embodiments, the solidification operation may be succeeded by apre-treatment operation prior to additional flowable oxide deposition.For example, this may involve exposure to an inert plasma followed byexposure to an oxidizing pre-treatment plasma. The flowable oxidedeposition and treatment operations are repeated until the desiredamount of flowable oxide is deposited. In the depicted embodiment, thisis enough only to partially fill the gap, though in other embodiments,it may be to fully fill the gap. In the depicted embodiment, gap fill isthen completed with HDP oxide deposition. (Block 1207). Densification orother treatments may be performed prior to the HDP oxide deposition.

Apparatus

The methods of the present invention may be performed on a wide-range ofapparatuses. The deposition operations may be implemented on any chamberequipped for deposition of dielectric film, including HDP-CVD reactors,PECVD reactors, sub-atmospheric CVD reactor, any chamber equipped forCVD reactions, and chambers used for PDL (pulsed deposition layers),with the treatment operations performed using these or other chambers.

Generally, an apparatus will include one or more chambers or “reactors”(sometimes including multiple stations) that house one or more wafersand are suitable for wafer processing. Each chamber may house one ormore wafers for processing. The one or more chambers maintain the waferin a defined position or positions (with or without motion within thatposition, e.g. rotation, vibration, or other agitation). While inprocess, each wafer is held in place by a pedestal, wafer chuck and/orother wafer holding apparatus. For certain operations in which the waferis to be heated, the apparatus may include a heater such as a heatingplate.

FIG. 13 depicts example tool configuration 1300 in which the toolincludes two high density plasma chemical vapor deposition (HDP-CVD)modules 1310, flowable gap fill module 1320, WTS (Wafer Transfer System)1340, loadlocks 1350, in some embodiments including a wafer coolingstation, and vacuum transfer module 1335. HDP-CVD modules 1310 may, forexample, be Novellus SPEED MAX modules. Flowable gap fill module 1320may, for example, be a Novellus Flowable Oxide module.

FIG. 14 is a simplified illustration of various components of a HDP-CVDapparatus that may be used for deposition of HDP oxide and pre- and/orpost-deposition treatment or cures according to various embodiments.Also in certain embodiments, it may be used for flowable oxidedeposition. As shown, a reactor 1401 includes a process chamber 1403which encloses other components of the reactor and serves to contain theplasma. In one example, the process chamber walls are made fromaluminum, aluminum oxide, and/or other suitable material. The embodimentshown in FIG. 14 has two plasma sources: top RF coil 1405 and side RFcoil 1407. Top RF coil 1405 is a medium frequency or MFRF coil and sideRF coil 1407 is a low frequency or LFRF coil. In the embodiment shown inFIG. 14, MFRF frequency may be from 430-470 kHz and LFRF frequency from340-370 kHz. However, apparatuses having single sources and/or non-RFplasma sources may be used.

Within the reactor, a wafer pedestal 1409 supports a substrate 1411. Aheat transfer subsystem including a line 1413 for supplying heattransfer fluid controls the temperature of substrate 1411. The waferchuck and heat transfer fluid system can facilitate maintaining theappropriate wafer temperatures.

A high frequency RF of HFRF source 1415 serves to electrically biassubstrate 1411 and draw charged precursor species onto the substrate forthe pre-treatment or cure operation. Electrical energy from source 1415is coupled to substrate 1411 via an electrode or capacitive coupling,for example. Note that the bias applied to the substrate need not be anRF bias. Other frequencies and DC bias may be used as well.

The process gases are introduced via one or more inlets 1417. The gasesmay be premixed or not. The gas or gas mixtures may be introduced from aprimary gas ring 1421, which may or may not direct the gases toward thesubstrate surface. Injectors may be connected to the primary gas ring1421 to direct at least some of the gases or gas mixtures into thechamber and toward substrate. The injectors, gas rings or othermechanisms for directing process gas toward the wafer are not present incertain embodiments. Process gases exit chamber 1403 via an outlet 1422.A vacuum pump typically draws process gases out and maintains a suitablylow pressure within the reactor. While the HDP chamber is described inthe context of pre- and/or post-deposition treatment or cure, in certainembodiments, it may be used as a deposition reactor for deposition of aflowable film. For example, in a thermal (non-plasma) deposition, such achamber may be used without striking a plasma.

FIG. 15 shows an example of a reactor that may be used in accordancewith certain embodiments of the invention. The reactor shown in FIG. 15is suitable for both the dark (non-plasma) or plasma-enhanced depositionas well as cure, for example, by capacitively-coupled plasma anneal. Asshown, a reactor 1500 includes a process chamber 1524, which enclosesother components of the reactor and serves to contain the plasmagenerated by a capacitor type system including a showerhead 1514 workingin conjunction with a grounded heater block 1520. A low-frequency RFgenerator 1502 and a high-frequency RF generator 1504 are connected toshowerhead 1514. The power and frequency are sufficient to generate aplasma from the process gas, for example 400-700 W total energy. In theimplementation of the present invention, the generators are not usedduring dark deposition of the flowable film. During the plasma annealstep, one or both generators may be used. For example, in a typicalprocess, the high frequency RF component is generally between 2-60 MHz;in a preferred embodiment, the component is 13.56 MHz.

Within the reactor, a wafer pedestal 1518 supports a substrate 1516. Thepedestal typically includes a chuck, a fork, or lift pins to hold andtransfer the substrate during and between the deposition and/or plasmatreatment reactions. The chuck may be an electrostatic chuck, amechanical chuck or various other types of chuck as are available foruse in the industry and/or research.

The process gases are introduced via inlet 1512. Multiple source gaslines 1510 are connected to manifold 1508. The gases may be premixed ornot. The temperature of the mixing bowl/manifold lines should bemaintained at levels above the reaction temperature. Temperatures at orabove about 80 C at pressures at or less than about 20 Torr usuallysuffice. Appropriate valving and mass flow control mechanisms areemployed to ensure that the correct gases are delivered during thedeposition and plasma treatment phases of the process. In case thechemical precursor(s) is delivered in the liquid form, liquid flowcontrol mechanisms are employed. The liquid is then vaporized and mixedwith other process gases during its transportation in a manifold heatedabove its vaporization point before reaching the deposition chamber.

Process gases exit chamber 1524 via an outlet 1522. A vacuum pump 1526(e.g., a one or two stage mechanical dry pump and/or a turbomolecularpump) typically draws process gases out and maintains a suitably lowpressure within the reactor by a close loop controlled flow restrictiondevice, such as a throttle valve or a pendulum valve.

FIG. 16 illustrates a simplified schematic of a remote plasmapre-treatment and/or cure module according to certain embodiments.Apparatus 1600 has a plasma producing portion 1611 and an exposurechamber 1601 separated by a showerhead assembly or faceplate 1617.Inside exposure chamber 1601, a platen (or stage) 1605 provides a wafersupport. Platen 1605 is fitted with a heating/cooling element. In someembodiments, platen 1605 is also configured for applying a bias to wafer1603. Low pressure is attained in exposure chamber 1601 via vacuum pumpvia conduit 1607. Sources of gaseous treatment gases provide a flow ofgas via inlet 1609 into plasma producing portion 1611 of the apparatus.Plasma producing portion 1611 may surrounded by induction coils (notshown). During operation, gas mixtures are introduced into plasmaproducing portion 1611, the induction coils are energized and a plasmais generated in plasma producing portion 1611. Showerhead assembly 1617may have an applied voltage and terminates the flow of some ions andallows the flow of neutral species into exposure chamber 1601.

Etching

As indicated, embodiments of the invention include non-selective andselective removal (etch) operations. According to various embodiments,non-selective etching of the HDP oxide and flowable oxide involvesexposing the dielectric layer to a plasma containing fluorine species.These species may originate from a fluorine-containing process gascomponent such as SiF₄, SiH₂F₂, Si₂F₆, C₂F₆, NF₃, CF₄, and the like.

Selective etching of the flowable oxide material may also involveexposing the dielectric layer to a plasma containing fluorine species.In other embodiments, it may be accomplished via a wet etch, e.g., a HFwet etch.

In certain embodiments, one or more of the etch operations involve adownstream etch process, in which the substrate is not directly exposedto a plasma. A remote plasma generator may be used to generate theplasma. In other embodiments, a sputter etch using a non-fluorinechemistry is used. The sputter etch chemistry may include one or more ofHe, Ar, O2 or H2. In certain embodiments, one or more of these gases arefed to a remote or in situ plasma generator. The etch processes may beperformed in the same or different chambers as the preceding depositionprocess.

FIGS. 13-16 provide examples of apparatuses that may be used toimplement the pre-treatments described herein. However, one of skill inthe art will understand that various modifications may be made from thedescription.

In certain embodiments, a system controller is employed to controlprocess parameters. The system controller typically includes one or morememory devices and one or more processors. The processor may include aCPU or computer, analog and/or digital input/output connections, steppermotor controller boards, etc. Typically there will be a user interfaceassociated with system controller. The user interface may include adisplay screen, graphical software displays of the apparatus and/orprocess conditions, and user input devices such as pointing devices,keyboards, touch screens, microphones, etc. The system controller may beconnected to any or all of the components shown in FIG. 13 of a tool;its placement and connectivity may vary based on the particularimplementation.

In certain embodiments, the system controller controls the pressure inthe processing chambers. The system controller may also controlconcentration of various process gases in the chamber by regulatingvalves, liquid delivery controllers and MFCs in the delivery system aswell as flow restriction valves an the exhaust line. The systemcontroller executes system control software including sets ofinstructions for controlling the timing, flow rates of gases andliquids, chamber pressure, substrate temperature, and other parametersof a particular process. Other computer programs stored on memorydevices associated with the controller may be employed in someembodiments. In certain embodiments, the system controller controls thetransfer of a substrate into and out of various components of theapparatuses shown in FIG. 13.

The computer program code for controlling the processes in a processsequence can be written in any conventional computer readableprogramming language: for example, assembly language, C, C++, Pascal,Fortran or others. Compiled object code or script is executed by theprocessor to perform the tasks identified in the program. The systemsoftware may be designed or configured in many different ways. Forexample, various chamber component subroutines or control objects may bewritten to control operation of the chamber components necessary tocarry out the described processes. Examples of programs or sections ofprograms for this purpose include process gas control code, pressurecontrol code, and plasma control code.

The controller parameters relate to process conditions such as, forexample, timing of each operation, pressure inside the chamber,substrate temperature, process gas flow rates, RF power, as well asothers described above. These parameters are provided to the user in theform of a recipe, and may be entered utilizing the user interface.Signals for monitoring the process may be provided by analog and/ordigital input connections of the system controller. The signals forcontrolling the process are output on the analog and digital outputconnections of the apparatus.

The above-described processes and apparatuses may deposit dielectric onany type of substrate that requires thin dielectric layers. Often, thesubstrate will be a semiconductor wafer having gaps in need ofdielectric filling. The invention is not, however, limited to suchapplications. It may be employed in a myriad of other fabricationprocesses such as for fabricating flat panel displays.

As indicated above, this invention may be used in integrated circuitfabrication. The gap filling processes are performed on partiallyfabricated integrated circuits employing semiconductor substrates. Inspecific examples, the gap filling processes of this invention areemployed to form shallow trench isolation (STI), inter-metal layerdielectric (ILD) layers, passivation layers, etc. In certainembodiments, the methods described herein may be applied to integrationprocesses using flowable oxide deposition and any solid dielectricdeposition technique, including atomic layer deposition (ALD) and pulseddeposition layer (PDL) techniques. The disclosed methods and apparatusesmay also be implemented in systems including lithography and/orpatterning hardware for semiconductor fabrication. Further, thedisclosed methods may be implemented in a process with lithographyand/or patterning processes preceding or following the disclosedmethods.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theappended claims. It should be noted that there are many alternative waysof implementing the processes, systems and apparatus of the presentinvention. Accordingly, the present embodiments are to be considered asillustrative and not restrictive, and the invention is not to be limitedto the details given herein.

1. An apparatus comprising: a flowable dielectric deposition chamberconfigured to deposit flowable dielectric film; and a controller, saidcontroller comprising instructions for introducing into the flowabledielectric deposition chamber a process gas comprising asilicon-containing precursor, wherein the silicon-containing precursoris characterized by having a partial pressure (Pp):vapor pressure (Pvp)ratio of 0.01-1.
 2. The apparatus of claim 1, further comprising a highdensity plasma chemical vapor deposition (HDP-CVD) deposition chamberconfigured to deposit HDP dielectric film.
 3. The apparatus of claim 2,wherein the controller further comprises instructions for transferring asubstrate from the flowable dielectric deposition chamber to the HDP-CVDchamber after introducing the process gas to the flowable dielectricdeposition chamber.
 4. The apparatus of claim 3, wherein the controllerfurther comprises instructions to deposit HDP dielectric film aftertransferring the substrate.
 5. The apparatus of claim 1, wherein theflowable dielectric deposition chamber comprises a plasma generator. 6.The apparatus of claim 6, wherein the controller further comprisesinstructions to, after introducing the process gas to the flowabledielectric deposition chamber, generate a high-density plasma in theplasma generator and deposit HDP dielectric film.
 7. The apparatus ofclaim 1, wherein the process gas further comprises an oxidant, whereinthe wherein the oxidant is characterized by the following partialpressure (Pp):vapor pressure (Pvp) ratio: 0.25-2.
 8. The apparatus ofclaim 1, wherein the process gas further comprises a solvent, whereinthe wherein the solvent is characterized by having a partial pressure(Pp):vapor pressure (Pvp) ratio of 0.1-1.
 9. A method, comprising:introducing a process gas comprising a silicon-containing precursor andan oxidant to a deposition, wherein the process gas is characterized ashaving an oxidant:precursor partial pressure ratio of about 5 to 15 tothereby deposit a flowable dielectric film on a substrate in the processchamber.
 10. The method of claim 9, wherein the process gas furthercomprises a solvent.
 11. The method of claim 9, further comprising adepositing a high density plasma chemical vapor deposition (HDP-CVD)dielectric film via a high density plasma chemical vapor depositionreaction on the flowable dielectric film.
 12. A method of depositing adielectric film on a substrate, the method comprising: introducing aprocess gas comprising a silicon-containing precursor to thereby deposita flowable dielectric film on the substrate, wherein thesilicon-containing precursor is characterized by having a partialpressure (Pp):vapor pressure (Pvp) ratio of 0.01-1.
 13. The method ofclaim 12, wherein the process gas further comprises an oxidant, whereinthe wherein the oxidant is characterized by the following partialpressure (Pp):vapor pressure (Pvp) ratio 0.25-2.
 14. The method of claim12, wherein the process gas further comprises a solvent, wherein thewherein the solvent is characterized by the following partial pressure(Pp):vapor pressure (Pvp) ratio 0.1-1.
 15. The method of claim 12,further comprising depositing a high density plasma (HDP) dielectricfilm on the flowable dielectric film.
 16. The method of claim 12,wherein the flowable dielectric film is a silicon oxide film, a siliconnitride film or a silicon oxynitride film.